Apparatus for measuring color



Aug. 29, 1933. NICKERSQN 1,924,747

APPARATUS FOR MEASURING COLOR Filed Nov. 13, 1928 INVENT DR II EIRCI THYNIEKERE UN AT TDRNEY Patented Aug. 29, 1933 APPARATUS FOR MEASURINGCOLOR,

Dorothy Nickerson, Washington, D. 0.

Application November 13, 1928 Serial No. 319,158

, 1 Claim.

(Granted under the Act of March 3, 1883, as

amended April 30,

This application is made under the act approved April 30, 1928, and theinvention herein described, may be manufactured and used by or for theGovernment for governmental purposes 5 without payment to me of anyroyalty thereon.

My invention relates particularly to measurement of the color of rawcotton, or other substance containing foreign matter or otherwisepresenting a non-uniform field for comparison with the standard, but itis evident that it may also be applied to objects presenting a uniformsurface. The features peculiar to my invention are: means of viewing alarge enough area of the variegated field to be fairly representative;means of rendering invisible the details of this field for bettercomparison; rapid means'of synthesizing and analyzing the comparisonfield; and means of securing proper illumination of both fields.

The apparatus used in carrying out my invention is a peculiar form ofcolorimeter making use of the Maxwell color disks for the comparisonfield. These are peculiarly suited to my in vention because by them thethree fundamental units of color, hue, brilliance, and chroma may begiven numerical expression. They are cut radially so that they may bescrewed into each other and present a circular area composed of segmentsof different colors. The colorimeter contains also the well-knownoptical means of condensing a large enough field to be representative toa small enough field to be compared; an optical means of off-focusing toremove detail in the object; a method of integrating the segments of thediscs into a uniform color; the usual photometric cube; a suitablemethod of illumination; and a holder for the object. I can accomplish myresults by means of either the apparatus shown in the accompanyingdrawing which consists of an eyepiece, discs, a holder, and suitablelighting or by the apparatus shown in the drawing in which Figure 1 isside view of the colorimeter and object holder, Figure 2 a front view ofthe colorimeter and means of illumination, and Figure 3 a top view ofthe segrhomb 7 and mounted on base 1 carries color discs 10.Illuminating means 11 are mounted on the front of base 1 and are sopositioned as to cast uncolored rays of equal light simultaneously onsample situated upon sample holder 2 and on color discs 10. Thetelescope assembly 5 is mounted on base 1 by means of bracket land is sopositioned as to permit simultaneous observance of discs 10 and sampleon sample holder 2. V

The effect of the rotation of the rhomb is to gather light from allparts of the irregular annular area presented by the segments of thesample, and lead it into the cube and into the eye. Light also comesfrom the discs into the telescope assembly and the eye. This light maycome from a non-uniform field and must be off focused in order to removethedetail. The same train of lenses used in off focus may also be usedto condense a large enough field of the object to be representative ofits general character. I

to proper proportions;

The sources of light may be two lamps symmetrically placed withreference to both fields andpreferably of about 5,000 K colortemperature. there is an equilization of the amount and quality of lightseen through the eyepiece from the sample and the discs.

I claim: l

A colorimeter of the character described, the combination with a base, asample holder mounted on the rear of said base, means for mounting colordisks, having percentage graduations thereon, in operative relation tothe sample holder, means for revolving said disks, illuminating meansmounted on the'front of the base and so positioned as to cast uncoloredrays of equal light simultaneously on sample and on color disks, and atelescope assembly mounted on said base so positioned as to permitsimultaneous observance of said disks and sample.

DOROTHY NICKERSON.

The sample holder 2 is to limit the objective field They must'becarefully adjusted so that

